Method and apparatus for employing dynamic range mapping information for HDR image decoder considering backward compatibility

Abstract

The present invention enables efficient decoding by using DR mapping information between a base layer and an enhancement layer in various manners in an HDR decoder considering backward compatibility.

What is claimed is: 
     
       1. A method of decoding an image performed by an image decoding apparatus, the method comprising:
 analyzing an image characteristic of a current image by using one or more pixels of a current block and one or more pixels of a neighboring block; 
 determining mapping information based on the analyzed image characteristic; and 
 decoding the current image based on the mapping information, 
 wherein the mapping information is determined for at least one of a plurality of intervals, the plurality of intervals being obtained by dividing a luminance range for the current image, and 
 wherein determining the mapping information comprises modifying, based on the analyzed image characteristic, the mapping information using modification information corresponding to an interval of the current image, 
 wherein the interval of the current image is representative of one of the plurality of intervals, 
 wherein the modification of the mapping information is performed based on a flag transmitted from an image encoding apparatus, 
 wherein the image decoding apparatus receives a bitstream from the image encoding apparatus, 
 wherein the bitstream includes a video parameter set (VPS) and a sequence parameter set (SPS), 
 wherein the modification information is included in the sequence parameter set, 
 wherein the modification information is received, from the bitstream, for each of the plurality of intervals, and 
 wherein the modification information comprises information on a position of the interval and a modification value needed for the modification. 
 
     
     
       2. A method of encoding an image performed by an image encoding apparatus, the method comprising:
 analyzing an image characteristic of a current image by using one or more pixels of a current block and one or more pixels of a neighboring block; 
 determining mapping information based on the analyzed image characteristic; and 
 encoding the current image based on the mapping information, 
 wherein the mapping information is determined for at least one of a plurality of intervals, the plurality of intervals being obtained by dividing a luminance range for the current image, and 
 wherein determining the mapping information comprises modifying, based on the analyzed image characteristic, the mapping information using modification information corresponding to an interval of the current image, 
 wherein the interval of the current image is representative of one of the plurality of intervals, 
 wherein a flag that is a basis for performing the modification of the mapping information is encoded by the image encoding apparatus, 
 wherein the image encoding apparatus transmits a bitstream to an image decoding apparatus, 
 wherein the bitstream includes a video parameter set (VPS) and a sequence parameter set (SPS), 
 wherein the modification information is encoded into the sequence parameter set, 
 wherein the modification information is encoded for each of the plurality of intervals, and 
 wherein the modification information comprises information on a position of the interval and a modification value needed for the modification. 
 
     
     
       3. A non-transitory computer-readable recording medium for storing data associated with a video signal, comprising:
 a bitstream stored in the non-transitory computer-readable medium, the bitstream comprising a flag that is a basis for performing modification of mapping information, 
 wherein the mapping information is basis for decoding a current image, 
 wherein an image characteristic of the current image is analyzed by using one or more pixels of a current block and one or more pixels of a neighboring block, 
 wherein, based on the analyzed image characteristic of the current image, the mapping information is determined for at least one of a plurality of intervals 
 wherein the plurality of intervals being obtained by dividing a luminance range for the current image, 
 wherein the mapping information is determined by modifying, based on the analyzed image characteristic, the mapping information using the modification information corresponding to an interval of the current image, 
 wherein the interval of the current image is representative of one of the plurality of intervals, 
 wherein the bitstream includes a video parameter set (VPS) and a sequence parameter set (SPS), 
 wherein the modification information is included in the sequence parameter set, 
 wherein the modification information for each of the plurality of intervals is included in the bitstream, and 
 wherein the modification information comprises information on a position of the interval and a modification value needed for the modification. 
 
     
     
       4. A method of transmitting a bitstream generated by encoding an image using an encoding method performed by an image encoding apparatus, the encoding method comprising:
 analyzing an image characteristic of a current image by using one or more pixels of a current block and one or more pixels of a neighboring block; 
 determining mapping information based on the analyzed image characteristic; and 
 encoding the current image based on the mapping information, 
 wherein the mapping information is determined for at least one of a plurality of intervals, the plurality of intervals being obtained by dividing a luminance range for the current image, and 
 wherein the determining the mapping information comprises modifying, based on the analyzed image characteristic, the mapping information using modification information corresponding to an interval of the current image, 
 wherein the interval of the current image is representative of one of the plurality of intervals, 
 wherein a flag that is a basis for performing the modification of the mapping information is encoded by the image encoding apparatus, 
 wherein the bitstream includes a video parameter set (VPS) and a sequence parameter set (SPS), 
 wherein the modification information is encoded into the sequence parameter set, 
 wherein the modification information is encoded for each of the plurality of intervals, and 
 wherein the modification information comprises information on a position of the interval and a modification value needed for the modification.